Take this, smug marrieds: 5 ways love does the body bad

A spiteful spouse can be as bad for your health as smoking

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On Valentine's Day, the sight of couples holding hands and exchanging kisses might unleash a wave of jealousy in those who are single.

However, there might not be much to be jealous about. Relationships can be fraught with sadness, anger, confusion and stress. Here are five examples of how relationships — especially strained ones — can be bad for your health.

Increased risks of coronary heart disease
A stressful relationship or marriage can leave you vulnerable and heartbroken — literally. According to a 2000 study published in the Journal of the American Medical Association, women who reported moderate to severe marital strain were 2.9 times more likely to need heart surgery, suffer heart attacks or die of heart disease than women without marital stress. This finding held even when researchers adjusted for other factors such as age, smoking habits, diabetes, blood pressure and "bad" cholesterol levels.

And unmarried women living with their sweeties who were in severely stressful relationships also had a higher risk of heart problems, the study showed.

These results were echoed by another study published in the American Journal of Cardiology in 2006, which showed that marital quality and social support are especially important in the development and management of chronic diseases such as congestive heart failure. The study found that patients with the most severe heart disease and poorest marriages had the highest risk of dying over a four-year period. The four-year survival rate of those with severe heart disease and poor marriages was 42 percent, compared with 78 percent among patients with milder heart disease and good marriages.

Poor mental health
Although studies have shown that a steady, committed relationship is good for mental health, a difficult and strained relationship — perhaps unsurprisingly — has the opposite effect. Negative behaviors, such as hostility and criticism, during conflict in relationships have been linked to negative impacts on mental health. In fact, according to a 2003 article in the Journal of Health and Social Behavior, single people tend to have better mental health than those who remain in a tumultuous relationship.

And going through too many breakups might be worse for your health than staying single. A British study published in 2004 in the Journal of Epidemiology and Community Health found that living through multiple partnership transitions, such as divorces and separations, adversely affected women's mental health. The researchers studied 2,127 men and 2,303 women, and found that women who went through several such breakups tended to have worse mental health than women who remained single all their lives.

Negative effects on overall health
Not only can an unhappy marriage can drag down your spirits, it can drag down your health too. Studies have shown that ill-effects of marital stress for women are on par with more traditional health risk factors, such as physical inactivity and smoking.

Women who experienced more conflicts and disagreements in their relationships also had a higher risk of high blood pressure, abdominal obesity, high blood sugar, high triglycerides and low levels of "good" high-density lipoprotein cholesterol, according to a study of 276 couples presented in the 2009 American Psychosomatic Society's annual meeting. The study also found the wives to be more affected than the husbands.

Marital conflict also has been linked to immune system disruptions. According to a 1993 article in the journal Psychosomatic Medicine, newlywed couples involved in a 30-minute heated discussion of marital problems tended to have relatively poorer immunological responses, unlike couples engaged in positive or problem-solving behaviors.

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Heaping stress upon stress
Marital distress can be a chronic stressor. According to a 2003 review in the journal Physiology and Behavior, distressed marriages are a major source of stress for couples. In fact, unhappily married people are generally are worse off in their well-being than unmarried people, the study found.

And marital stress can spill over into the workplace too. According to a 2005 article in the Annals of Behavioral Medicine, domestic strain can influence how well people function over the workday, away from home. The researchers measured the blood pressure and levels of the stress hormone cortisol of 105 middle-age men and women, and compared them to the self-reported stress levels.

They found that those with more marital concerns reported greater stress throughout the day, had higher blood pressure in the middle of the workday and higher morning cortisol levels. These factors can, over time, combine to increase the risk of obesity, diabetes, depression, heart attack and stroke, the study said.

Slower disease recovery
Relationship conflict and distress are associated with poorer physical health in terms of the severity of disease symptoms and degree of recovery.

Marital distress was associated with worse recovery trajectory for breast cancer survivors, according to a 2009 study published in the journal Cancer. Patients in a distressed relationship not only had continuously heightened levels of stress, they also eventually showed more impaired functioning compared with those in stable, non-distressed relationships, said the study. In addition, patients dissatisfied with their marriage were also less compliant with medical regimens, such as adhering to healthy dietary habits.